Expected to increase light rail ridership and support more than 50,000 trips per day, the Green Line Extension (GLX) project has transformed transit service, accessibility and mobility for an entire region.

Headed by the Massachusetts Bay Transportation Authority (MBTA), the extended rail line travels from a newly relocated and reconstructed Lechmere Station in East Cambridge to the towns of Somerville and Medford. In addition to the Lechmere Station, the design-build project also consists of six new stations along the line.

The overall elements of the project include:

  • 3 miles of double track transit construction
  • Relocation of the Lechmere Station
  • Construction of six additional stations
  • Construction of a vehicle maintenance and storage facility
  • Construction of a 76-rail car layover/storage facility
  • 5 miles of new rail viaduct on complex alignments through dense urban site
  • Rail systems, including four substations
  • Reconstruction of eight highway bridges
  • Construction of noise and retaining walls
  • Track, signal, power and communication systems
  • The Somerville Community Path Extension

As part of final design services for the GLX project, HNTB led the rail/transit and line structure design. Initially, before the MBTA decided to change the project to a design-build approach, HNTB was not only responsible for the design of the new structure, but also served as designer for the relocation of the original, adjacent commuter rail track.

Once the GLX became a design-build project, HNTB continued to support the MBTA throughout the life cycle of the extension project. In this phase, the firm also provided scheduling, safety and security, systems integration, testing and commissioning, and MBTA operations interface services.

The Somerville Community Path Extension

The final element of the project, the Somerville Community Path runs alongside the Medford branch of the newly extended light rail line for a little over two miles. Open to pedestrians and cyclists, the path connects with the popular Minuteman Trail. Together, the multi-use paths are estimated to serve over 900,000 people from the surrounding communities.

Extended Rail Lines Mean Extended Opportunity

The benefits of the GLX project continue to spread throughout the region. With increased public transit ridership and more access to pedestrian- and cyclist-friendly infrastructure, roadway vehicle emissions will significantly be reduced.

Not only is the completed MBTA project improving mobility, but the extended lines are also providing opportunity. With better connection to surrounding neighborhoods, jobs and more, the light rail line is set to support plans for extensive local development and economic growth across Massachusetts communities.

Location: Cambridge, Somerville, Medford, MA

Client: Massachusetts Bay Transportation Authority (MBTA)